Some of the worst serial-killers were deeply religious ("even after all I did, I know God forgives all"); doesn't that hint that you don't need to be religious to be nice?
If someone decided to believe something completely wacko (like scientology) and then called it a religion; does that reflect meaningfully on the other religions? If someone called themselves a "Christian" or "Buddhist", but then did something obviously un-Christian, un-Buddhist, and un-nice, does it mean that Christianity or Buddhism are necessarily evil or un-nice? The same can be said for atheism. Hitler was not nice; if he had applied Christianity or Scientology, would he have turned out better? No way to tell.
I would say that you have to evaluate each person individually, and how they apply their religion, and then see whether it made a positive or negative difference in that one case. Whether supposedly "religious" people either do or do not behave better or worse than their neighbors doesn't have much significance beyond their specific case. Even then, it is hard to know how they would have turned out otherwise.
No one ever hears about the religious people who didn't become serial killers because of their religion, precisely because they didn't, and there is no way to know that they would have.
Every generalization is wrong.
The label "religion" poisons (or at least confuses) everything.
If a particular religion were seriously applied to its fullest, should it make a person better or not? This method helps separate individual variability from the actual effects of religion.
Note that many religions include evangelism or actual belief as part of application, which many may not consider "nice". If you believe your religion, it often means that you don't believe another person's, and that could be construed as intolerant, and thus un-nice.
Therefore, you may consider it to be impossible for religion to make a person "nice", since it often comes with these nasty side effects. In that case, you are probably also being intolerant and un-nice yourself.
From what I can tell, there are several religions (such as Christianity) that require you to be a "better" person if you actually apply it. In that sense, then yes, religion can make you a better person. Does that mean that you can't be a "good" person without religion? Of course not.
At the same time, Christianity states that it is impossible to apply Christianity without divine intervention, which brings into question whether "religion" itself makes you better, or God. Again, that doesn't mean that you can't be nice without God, only that it is (purportedly) impossible to reach the standards required by Christianity without His help.
There are also religions that arguably neither improve nor hurt someone's "goodness." Atheism is probably one of these. Nothing about atheism says that you need to be nicer than you are, but it doesn't make you more evil either.
And finally, there are some "religions" that have (according to everyone else, of course) entirely bad or evil effects when applied. The human sacrificial tendencies of the Aztecs were arguably in this category.
So, "religion" in general neither makes one nice or bad. Only specific religions, applied in a specific way have that result. And even then, who defines "good" or "bad"?
None of this belongs on HN though; religion is too close to the base of one's entire thought structure and world view, and thus debates concerning it are almost entirely inflammatory and unlikely to positively change either side's opinions.
Giving a vague definition to some philosophy/ideology/methodology then claiming the good things that arise out are inherent in it while saying the bad things that come out of it are external. Classic. (Sorry, I can't for the life of me express this clearly. There was an article on Agile recently that said it better than I can).
"All the serial killers are religious!" "All the genocidal Communists were atheists!" Etc.
I've pretty much come to the conclusion that all atheism/religion discussions on the Internet (even Hacker News) are guaranteed to get real stupid, real fast.
That mindset appeals to programmers, in part because it's a very lazy mindset that allows you to quickly judge complex things and focus on the very specific thing that you care to focus on. It's the same mindset that encourages blind libertarianism. The problem with it is that it discourages intellectual discussion and leads to flame wars. That's what brought reddit down: a mass of people who were willing to instantly denounce people, and who led to a very hive-mind situation.
PS: This is an ugly topic and a terrible article. Can we please get some moderation in here?